1. Field of the Invention
This invention relates to the compound 13-oxabicyclo(10.4.0)-hexadec-1(12)-en-14-one having the formula (1): ##STR1##
This invention relates also to a method of preparing that compound. The compound is an important intermediate for producing musk perfume fragrance ingredient.
The starting materials employable in this invention are .beta.-(2-oxocyclododecyl)propionic acid and derivatives thereof, having the formula: ##STR2## wherein R is --OH, --OCH.sub.3, --OC.sub.2 H.sub.5, --Cl, --Br, ##STR3##
The compound .beta.-(2-oxocyclododecyl)propionic acid, for example, can be prepared by the following steps: dehydrationcondensation of cyclododecanone and morpholine by the method described in Japenese Patent Publication No. Showa 44-60 to give 1-N-morpholino-1-cyclododecene, which is reacted with .beta.-bromopropionic acid and then hydrolyzed. Other derivatives, such as the methyl and ethyl esters, acid chloride, acid bromide, and acetoxy derivatives are obtained from .beta.-(2-oxocyclododecyl)propionic acid by the usual methods for transforming acids to those derivatives.
Also its morpholine amide derivative, wherein R is ##STR4## in formula (2), is prepared by the reaction of 1-N-morpholino-cyclododecene with .beta.-propiolactone. The morpholine amide derivative is a novel compound.
The inventors have established a more effective method for producing .beta.-(2-oxocyclododecyl)propionic acid by the following steps: reacting cyclododecanone with diethyl carbonate to give carbethoxycyclododecanone, reacting the carboethoxycyclododecanone with .beta.-propiolactone in a solvent having no alkoxy group, such as benzene, toluene and ethyl ether in the presence of sodium hydride, hydrolyzing the resulting product, and then decarboxylating to give .beta.-(2-oxocyclododecyl)propionic acid in high yield (79% based on the starting cyclododecanone theoretically).
A conventional process for preparing .beta.-(2-oxocyclododecyl) propionic acid from 2-carbethoxycyclododecanone is disclosed in USP at No. 3,778,483. According to that patent, 2-carbethoxycyclododecanone is reacted with an acrylic ester in the presence of sodium alkoxide in an alcohol as a solvent and then the resulting intermediate is hydrolyzed to obtain .beta.-(2-oxocyclododecyl)propionic acid. On the contrary, the foregoing process of this invention is a novel process. It does not involve any compound having an alkoxy group as a solvent, a basic substance as well as starting materials, whereby it can be effected without production of any intermediate. According to this invention, the carbethoxy group is merely removed by hydrolyzation and decarboxylation. Furthermore, the molar proportion of .beta.-propiolactone to 2-carbethoxycyclododecanone is as low as from one to one and half. On the other hand, that of the molar proportion of methyl acrylate to 2-carbethoxycyclododecanone according to Example 19 of that patent is as high as three.
The new compound provided in this invention, namely, 13-oxabicyclo(10.4.0)haxadec-1(12)-en-14-one, is a very important intermediate for the preparation of cyclopentadecanone by the following steps as shown in the reaction schemes set forth below: (a) oxidation cleavage of the C=C bond of the formula (1) compound with ozone, (b) Wolff-Kishner reduction of the resulting 4-oxopentadecanedioic acid and esterification of the acid with methanol, (c) acyloin condensation of the dimethyl pentadecanedioate, and finally (d) reduction of the resultant acyloin. The step (c) and (d) is disclosed in Hiroo YONETANI and Masao KUBO, The Koryo, 48(1958), page 22-25 (published by Nippon Koryo Kyokai). ##STR5##
As described later in the Examples, the cyclopentadecanone was obtained from cyclododecanone through the new intermediate in this invention, 13-oxabicyclo(10.4.0)hexadec-1(12)-en-14-one in 39.7% yield (total yield based on the starting cyclododecanone).
There have been proposed many methods for producing cyclopentadecanone from many starting materials such as undecylenyl bromide, cyclododecanone, and others. The method using undecylenyl bromide as starting material, described in Indian J. Chem., 2, 355 (1964) by M. S. R. Nair et al., can produce cyclopentadecanone through 5-oxopentadecanedioic acid, which has a structure similar to 4oxopentadecanedioic acid, which latter compound is an ozone-oxidation product of 13-oxabicyclo(10.4.0)hexadec-1(12)-en-14-one, as set forth in step (a) of the reaction scheme given above. However, this method has the following disadvantages: (a) the starting material undecylenyl bromide cannot be supplied constantly, (b) the waste water treatment is troublesome because the method includes an oxidation process by potassium permanganate or chromic acid, the heavy metal of which is a nuisance to public health, and (c) the use of a Grignard reagent causes many safety troubles.
Other methods using cyclododecene as described in Japanese Patent Publication No. Showa 46-17,227 and No. Showa 49-4,459 have low yields (level of 20%). Further, the method described in Japanese Patent (unexamined) No. Showa 48-54,044 is disadvantageous for reasons of safety, because a Grignard reagent is applied in the process of this method. Thus, no method for preparing cyclopentadecanone has been provided which is fully satisfactory from all standpoints.
Contrary to these methods, the method of this invention provides a new intermediate which is useful for producing cyclopentadecanone in high yield without causing any trouble from the standpoint of safe operation and environmental pollution. Cyclopentadecanone is useful for musk perfume fragrance, which is disclosed in USP 3,778,483.